The U.S. Geological Survey’s National Water-Quality Assessment program requires nutrient input information for analysis of national and regional assessment of water quality. Historical data are needed to lengthen the data record for assessment of
Gronberg, Jo Ann M.,Ludtke, Amy S. asludtke@usgs.gov,Knifong, Donna L. dknifong@usgs.gov. Estimates of inorganic nitrogen wet deposition from precipitation for the conterminous United States, 1955-84. 2014-01-01.